Exchange apparatus

ABSTRACT

An exchange apparatus comprised of hollow thermoplastic tubes infusion bonded into a thermoplastic material is disclosed. In a preferred embodiment the hollow tubes are shaped by plaiting the tubes into cords and then thermally annealing the cords to set the crests and bends of the plait. The cords provide improved flow distribution of fluid about the hollow tube tubes in the exchange apparatus. The exchange apparatus is chemically inert and is useful for cross flow filtration, as well as heat and mass transfer in harsh chemical environments.

RELATED APPLICATIONS

[0001] This application claims the benefit of provisional applicationSer. No. 60/326,234 filed Oct. 1, 2001 entitled Fluid Exchange Device.This application is related to co-pending application filed concurrentlyherewith as U.S. Ser. No. 60/326,357, filed Oct. 1, 2001 underApplicants' reference number 200100293 (formerly MYKP-621).

FIELD OF INVENTION

[0002] This invention relates to a hollow tube or hollow fiber membraneexchange apparatus useful for heat transfer, particle filtration, andmass transfer applications. The apparatus comprises a housing containingfusion bonded hollow tubes that have been previously plaited andthermally annealed to set the plait. The apparatus has a high packingdensity of hollow tubes with enhanced fluid flow distribution providedby the plaited hollow tubes. The apparatus provides high contacting areain a small volume without the need for baffles. The device is made fromchemically inert thermoplastic materials and has the ability to operateat elevated temperatures with organic as well as corrosive and oxidizingliquids.

BACKGROUND

[0003] Hollow fibers and thin walled hollow tubes are commonly used inmass transfer, heat exchange, and cross flow particle filtrationdevices. In these applications the hollow tubes or fibers provide a highsurface to volume ratio which permits a greater transfer of heat andmass in a smaller volume than a device made with flat sheet materials ofsimilar composition.

[0004] A hollow fiber or a hollow tube comprises an outer diameter andsurface, an inner diameter and surface, and a porous or non-porousmaterial between the first and second surfaces or sides of the tube orfiber. The inner diameter defines the hollow portion of the fiber ortube and is used to carry one of the fluids. For what is termed tubeside contacting, a first fluid phase flows through the hollow portion,sometimes called the lumen, and is maintained separate from a secondfluid phase, which surrounds the tube or fiber. In shell sidecontacting, the first fluid phase surrounds the outer diameter andsurface of the tube or fibers and the second fluid phase flows throughthe lumen. In an exchange apparatus, packing density relates to thenumber of useful hollow fiber or hollow tubes that can be potted in theapparatus.

[0005] Examples of applications in semiconductor manufacturing whereheating of a liquid is required include sulfuric acid and hydrogenperoxide photoresist strip solutions, hot phosphoric acid for siliconnitride and aluminum metal etching, ammonium hydroxide and hydrogenperoxide SC1 cleaning solutions, hydrochloric acid and hydrogen peroxideSC2 cleaning solutions, hot deionized water rinses, and heated organicamine based photoresist strippers.

[0006] Cooling of heated liquids after use in a bath, especiallyphotoresist stripping solutions, phosphoric acid, SC1 and SC2 cleaningsolutions is necessary prior to disposing of the used chemical.Electrochemical plating baths and apparatus are sometimes maintained atsub-ambient temperatures.

[0007] On a wafer processing track apparatus, accurate and repeatableconditioning of the temperature of liquids such as spin on dielectrics,photoresists, antireflective coatings, and developers prior to dispenseonto a wafer requires heating or cooling of these liquids.

[0008] Heat exchangers are devices which transfer heat from one fluid,the process fluid, and a second working fluid. Polymer based heatexchangers are used for heating and cooling chemicals for theseapplications due to their chemical inertness and resistance tocorrosion. However, polymeric heat exchange devices are usually largebecause a high heat transfer surface area is required to effect a giventemperature change due to the low thermal conductivity of the polymersused in the device. Braiding of the tubes is used prevent the tubes frombecoming unevenly spaced when used in open container heat exchangeapplications. Such devices take up valuable space, requires large holdupvolumes of chemicals or exchange fluid, and are costly to make. Suchdevices also require o-ring seals which are prone to failure and arealso a source of ionic and particulate contamination.

[0009] Quartz heaters are also used to heat liquids used forsemiconductor processing. Quartz is susceptible to breakage and exposedresistively heated surfaces pose fire and explosion hazards especiallyfor organic liquids and liquids which evolve flammable gases.

[0010] Gas to liquid contactors or exchangers using hollow fiber tubesare used in semiconductor manufacturing to remove or to add gases toliquids. Commercially available gas to liquid contactors utilize bafflesto improve mass transfer between the fluids. Typical applications forcontacting membrane systems are to remove dissolved gases from liquids,“degassing”, or to add a gaseous substance to a liquid. For example, awet bench is a wafer processing apparatus where ozone gas is added tovery pure water to be contacted with semiconductor wafers for cleaningand oxide growth.

[0011] Cross flow filtration is used in semiconductor manufacturing toremove suspended solids, such as abrasive particles used in chemicalmechanical polishing slurries. A chemical mechanical slurry streamcontains in addition to the solid slurry material, oxidizers likehydrogen peroxide in combination with acids and bases such ashydrochloric acid or ammonium hydroxide. A chemical mechanical polishingtool is an example of a wafer processing apparatus used in semiconductormanufacturing.

[0012] To effect cross flow filtration, mass transfer, or heat transferusing contactors made from hollow tubes or porous hollow fibers,baffling is commonly used to promote flow across the tubular elements.Various designs for baffling have been detailed in the literature whichimprove the transfer of heat and materials to the hollow tubes. U.S.Pat. No. 5,352,361 teaches the art of baffling for hollow fiber gas toliquid contactors. Such baffles are useful for polyethylene like hollowtubes where methods to pot and spin laminate baffles are easilyimplemented. Baffling of perfluronated tubes is not practical using thistechnique. U.S. Pat. No. 4,749,031 teaches baffling with perfluorinatedbaffles through which individual hollow tubes are threaded. It iscumbersome, and expensive to manufacture exchange contactors using thistechnique. U.S. Pat. No. 4,360,059 describes a spiral heat exchangerprepared from a cast material such as aluminum. Such a method does notcontemplate the use of thermoplastics nor does it address the need forthe substantially higher surface area required for low thermallyconductive thermoplastic materials.

[0013] U.S. Pat. No. 3,315,740 discloses a method of bonding tubestogether by fusion for use in heat exchangers. Tubes of a thermoplasticmaterial are gathered in a manner such that the end portions of thetubes are in a contacting parallel relationship. The end portion of thegathered tubes is placed within a sleeve having a thermoplastic internalsurface and being rigid relative to the tubes. A fluid heated to atemperature at least equal to the softening point of the thermoplasticmaterial is introduced into the interiors of the end portions of thetubes. Then a pressure differential is imposed across the walls of thetubes so that the pressure within the tubes is greater than the pressureon the exterior surfaces of the tubes, thereby causing the tubes to beexpanded and to be fused with the surfaces of the adjacent tubes. Such amethod produces an irregular pattern of entrances to the hollows of thetubes effecting non-uniform flow distribution to the tubes. Such amethod also requires relatively thick walled tubing to providesufficient thermoplastic to form a seal with the housing sleeve. It isnot contemplated to use such a potting method to form an end structureor a unified terminal end block, nor is it contemplated to braid thetubes and thermally set them prior to potting to provide enhanced flowdistribution.

[0014] Canadian Patent 1252082 teaches the art of making spiral woundpolymeric heat exchangers. Such a device requires mechanical fixtures tohold the tubes in place and as such requires a large volume of space.

[0015] U.S. Pat. Nos. 4,980,060 and 5,066,379 describe fusion bondedpotting of porous hollow fiber tubes for filtration. The invention doesnot disclose the conditions required to effect fusion bonding ofnon-porous thermoplastic tubes for preparation of a unified terminal endblock for use in phase and heat exchange. The invention does notcontemplate twisting or braiding of the hollow fibers nor does itcontemplate annealing the fibers prior to potting to effect a structureon the potted tubes for enhanced flow distribution.

[0016] Alan Gabelman and Sun-Tak Hwang in the Journal of MembraneScience, volume 159, pp 61-106, 1999 describe the importance of uniformfiber spacing for obtaining better mass transfer in hollow fibercontactors. The authors observe that hand built modules have moreuniform fiber spacing but that the cost of such modules do not justifytheir higher manufacturing cost. Such arguments can be applied to hollowtube heat exchange and cross flow devices as well.

[0017] U.S. Pat. No. 5,224,522 describes a method and device forproducing woven hollow fiber tapes for use in exchange devices such asblood oxygenators and heat exchangers. Such a device method requiresexpensive and complicated weaving equipment to fix the fibers in apreferred relationship in the tube mats.

[0018] Currently it is impractical to use thermoplastic heat exchangersfor large heat loads, shell side liquid flow, or efficient shell sidecross flow filtration because of the high expense and large size ofdevices needed. Metal heat exchangers are unacceptable for use insemiconductor manufacturing because of the corrosive nature of thechemicals and also because of the need to eliminate metallic andparticulate impurities from process liquids. What is needed is athermoplastic apparatus for heat exchange, mass transfer, or cross flowfiltration with high surface area, uniform fiber spacing, and minimalvolume. The apparatus should eliminate the need for baffles.

SUMMARY OF THE INVENTION

[0019] The present invention provides for an apparatus with high surfacearea useful in mass transfer, heat exchange, or cross flow particlefiltration. The apparatus is constructed of thermoplastic materials andcontains hollow thermoplastic fibers or hollow tubes fusion bonded intoa thermoplastic resin to form a unified terminal block. Optionally, theapparatus including the unified terminal block is fusion bonded into athermoplastic housing which has fluid inlet and fluid outlet connectionsfor the process and working fluids to be contacted across the hollowfibers or hollow tubes. A manufacturing method for the apparatus isprovided and described. A method of use of the apparatus is alsoprovided and described.

[0020] In one embodiment the hollow tubes in the apparatus are braided,plaited, or twisted together to create a cord of the tubes or fibersprior to fusion bonding into the thermoplastic resin to form a unifiedterminal block. Such cords provide enhanced flow distribution of fluidthrough the apparatus without the need for baffling. A high packingdensity of hollow tubes or cords is achieved with this invention.

[0021] In another embodiment the cord containing the hollow tubes orfibers is annealed in an oven to set the shape of the twist, plait, orbraid of the hollow tubes or fibers in place prior to the fusion bondingprocess. Alternatively, the hollow tube or cord can be wrapped around arod, another hollow tube, or a template and the shape of the hollow tubeor cord set by thermal annealing with the template. The braided ortwisted cord can be wound on a rack and thermally annealed setting thecord's plait, geometry, and length. The braided or twisted cords areremoved from the rack as a bundle of continuous cord which is thenfusion bonded into a thermoplastic resin to form a unified terminalblock. In an alternative embodiment, the annealed cord can be unwrappedto give individual non-circumfrential hollow tubes or fibers. Theseindividual hollow tubes are fusion bonded into a thermoplastic resinwell as a bundle. Optionally, the annealed cord or individualnon-circumfrential hollow tubes or fibers in the unified terminal blockare fusion bonded to a thermoplastic housing which has fluid inlet andfluid outlet connections for the process and working fluids to beexchanged by the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 (A-D) are schematic diagrams illustrating examples of atwisted and braided hollow tubes.

[0023]FIG. 2A is a schematic diagram, in cross section, of an exchangeapparatus with non-circumfrential hollow tubes fused in a thermoplasticresin.

[0024]FIG. 2B is a schematic diagram, in cross section, of an exchangeapparatus with non-circumfrential hollow tubes fused in a thermoplasticresin having fluid inlet and outlet connections.

[0025]FIG. 2C is a schematic diagram, in cross section, of an exchangeapparatus with non-circumfrential hollow tubes fused in a thermoplasticresin having fluid inlet and outlet connections and a housing with fluidconnections.

[0026]FIG. 3 is a schematic diagram, in cross section, of an exchangeapparatus with twisted hollow tubes fused in a thermoplastic resinhaving fluid inlet and outlet connections and a housing with fluidconnections.

[0027]FIG. 4 is a schematic diagram, in cross section, of an exchangeapparatus with braided hollow tubes fused in a thermoplastic resinhaving fluid inlet and outlet connections and a housing with fluidconnections.

[0028]FIG. 5 is a schematic diagram illustrating an end view of anexchange apparatus with braided hollow tubes fused in a thermoplasticresin having fluid inlet and outlet connections and a housing with fluidconnections.

[0029]FIG. 6 is a table detailing the performance of the heat exchangersdescribed in the Example 2 and Example 3.

[0030]FIG. 7 is a photomicrograph of hollow tube ends fusion bonded intoa thermoplastic resin using the method of this invention.

[0031]FIG. 8 is a Table detailing the performance of a twenty tube heatexchanger described in Example 6.

[0032]FIG. 9 is a Table detailing the performance of a 680 tube heatexchanger described in Example 7.

DESCRIPTION OF SPECIFIC EMBODIMENTS

[0033] This invention relates to an apparatus for heat and mass transferoperations as well as other phase separation applications. The presentinvention also describes a method for making a unified terminal endblock, fusion bonded exchange apparatus comprising braided or twistedthermoplastic hollow tubes or hollow fibers. A cord is referred to inthe practice of this invention as one or more fibers and or tubes whichhave been twisted together, plaited, or braided to form a unit which canbe potted or fused into a well of a thermoplastic resin by the method ofthis invention. The fusion bonding is performed with a thermoplasticpolymer. While the present invention will be described with reference tonon-porous poly(tetrafluoroethylene-co-perfluoromethylvinylether) hollowtubes, it is to be understood that the present invention can be madeusing a variety of thermoplastic tubes and or porous fiber membraneswhich will hereafter referred to in general as hollow tubes. Further,while the present invention is described with reference to twisted pairsof poly(tetrafluoroethylene-co-perfluoromethylvinylether) hollow tubes,it is to be understood that the present invention can be made using avariety of numbers of hollow tubes or hollow fibers which are twisted,woven, plaited, or braided to form what are hereafter referred to ascords. Finally, while the present invention is described with respect toan apparatus for heat exchange, similar devices utilizing porous hollowtubes or hollow fibers can be made for use in mass transfer and crossflow filtration applications.

[0034] For purposes of this invention, a single, un-wrapped annealedtube is considered a non-circumferential tube. Non-circumferential tubesare tubes with external dimensions that are not continuouslycircumferential on a longitudinal axis moving from one end portion ofthe tube to the other. Examples include, but are not limited to, ahelical coil, a permanently twisted hollow circular tubing such as thesingle, un-wrapped annealed fiber or a tube that is extruded in suchcondition, a triangular shaped tube or fiber, a rectangular shaped tubeor fiber, or a square shaped tube or fiber.

[0035] The braid, plait, twist, or non-circumfrential geometry of thehollow tubes or fibers provides for enhanced fluid distribution acrossand within the hollow tubes. The device provides high fluid contactingarea in a small volume without the need for baffles. The unitary orunified terminal block construction of the apparatus with chemicallyinert materials of construction eliminates the need for o-rings andpermits use of operation of the device at elevated temperatures and witha variety of fluids.

[0036] Two or more hollow tubes can be plaited, twisted or braided intoa cord manually or by use of commercially available winding and braidingequipment. In the practice of this invention a plurality of hollow tubescan be woven together to form mats of hollow tubes. For purposes of thisdisclosure and appended claims the terms mat and cord are usedinterchangeably. The number of twists of tube per foot in a cord isdefined by the distance λ₁ as illustrated in FIG. 1A. In FIG. 1A twotubes are shown twisted together, however any number of tubes can betwisted together to form a cord. In FIG. 1A the parameter λ₁ describesthe distance from crest to crest or bend to bend of the hollow tube 10twisted with hollow tube 12. A smaller value of the parameter λ, forexample λ₂ in FIG. 1B, illustrates a greater number of twists or bendsbetween hollow tubes 14 and 16. More than two hollow tubes can bebraided together to form a cord. For braided hollow tubes, asillustrated for individual tubes 18, 20, and 22 in FIG. 1C, a measure ofcord tightness is described by the parameter λ₃. Individual hollow tubes24, 26, and 28, as shown in FIG. 1D, are more tightly braided and so theparameter λ₄ is correspondingly smaller than λ₃. The value of λ canrange from 1 per foot to 50 per foot with a preferred range of 5-25crests or bends per foot. The number of hollow tubes twisted or braidedtogether to form a cord can range from 2 to 100, but is more preferablyfrom 2 to 10 hollow tubes.

[0037] The invention is described in more detail with reference to FIG.2A. As illustrated schematically in FIG. 2A, a portion of each end ofindividual thermoplastic non-circumfrential tubes 36, 38, and 40 arefusion bonded in a fluid tight matter with a thermoplastic resin to formtwo unitary end or unified terminal end block structures 32 and 34. Anynumber of thermoplastic hollow tubes can be fused into the thermoplasticresin. FIG. 2B illustrates a cross section of an exchange apparatusfurther comprising fluid connection ports 40 and 42 bonded to theunified terminal end blocks 34 and 32 with end caps 44 and 46. The endcaps and fluid connectors allow a first fluid from a source, not shown,to flow through the hollow tubes 36, 38, and 40. The two sides of thetypical hollow tube or hollow fiber 38 of this invention are furthercharacterized by the surfaces 37 and 39. FIG. 2C illustrates a crosssection of an exchange apparatus further comprising a housing 52 bondedto unified terminal end blocks 32 and 34 and having one or more fluidconnector ports 48 and 50.

[0038] In FIG. 3 an embodiment of the exchange apparatus is illustratedfurther comprising cords of twisted hollow tubes. The cords in thisillustration are comprised of hollow tubes 54 and 56, 58 and 60, and 62and 64. A portion of the ends of each cord are fusion bonded in a fluidtight manner with a thermoplastic resin to form the unified terminal endblocks 32 and 34. The apparatus can have optional housing 52 and endcaps 44 and 46 bonded to the unified terminal end blocks. In FIG. 3 atleast one fluid flow distributor 66 can optionally be press fit,threaded, or bonded into on or more of the housing fluid connectionports 48 and 50.

[0039] In FIG. 4 an embodiment of the exchange apparatus is illustratedfurther comprising cords of braided hollow tubes. The cords in thisillustration are comprised of three or more hollow tubes braidedtogether to form cords illustrated by 70 and 72. The ends of each cordare fusion bonded in a fluid tight manner with a thermoplastic resin tofor the unified terminal end blocks 32 and 34. The apparatus can haveoptional housing 52 and end caps 44 and 46 bonded to the unifiedterminal end blocks. In FIG. 4 at least one fluid flow distributor 66can optionally be press fit, threaded, or bonded into on or more of thehousing fluid connection ports 48 and 50. An end view of the exchangeapparatus shown in FIG. 4 is illustrated schematically in FIG. 5.

[0040] With reference to FIG. 3, the operation of one embodiment of thepresent invention as a heat exchanger will be described. A first fluidenters the exchange apparatus through fluid connection port 42 andenters the hollow tubes at openings 61 in the unified terminal end block32. Fluid flows through the interior or lumen of the hollow tubes andexits the tubes through the unified end block 34 at exit openings 63.The first fluid exits the exchange apparatus through fluid connectionport 40. A second fluid enters the exchange apparatus through housingfluid port 48 and optional flow distributor 66. The first fluid isseparated from a second fluid by the two surfaces and wall of the hollowtube. The second fluid enters the housing through connection 48 andsubstantially fills the space between the inner wall of the housing andthe outer diameters of the fibers. Energy is transferred between thefirst and second fluids through the thermoplastic hollow tube walls. Thesecond fluid exits the housing through the fluid connector port 50.Examples of fluids include liquids, vapors of liquids, gases, and supercritical fluids.

[0041] Manufacturers produce membranes from a variety of materials, themost general class being synthetic polymers. An important class ofsynthetic polymers are thermoplastic polymers, which can be flowed andmolded when heated and recover their original solid properties whencooled. As the conditions of the application to which a tube or membraneis being used become more severe, the materials that can be used becomeslimited. For example, the organic solvent based solutions used for wafercoating in the microelectronics industry will dissolve or swell andweaken some polymeric tubes and membranes. The high temperaturestripping baths in the same industry consist of highly acid andoxidative compounds, which will destroy membranes and tubes made ofcommon polymers.

[0042] Hollow tubes made from thermoplastics with outside diametersranging from 0.007 to 0.5 inches, and more preferably 0.025 to 0.1inches in diameter, and wall thickness ranging from 0.001 to 0.1 inches,preferably 0.003 to 0.05 inches in thickness, are useful in the practiceof this invention. The tubes can be used individually, or the tubes canbe combined by braiding, plaiting, or twisting them to form cordscomprised of multiple hollow tubes.

[0043] Examples of perfluorinated thermoplastics or their blends whichare useful in the practice of this invention include but are not limitedto [Polytetrafluoroethylene-co-perfluoromethylvinylether], (MFA),[Polytetrafluoroethylene-co-perfluoropropylvinylether], (PFA),[Polytetrafluoroethylene-co-hexafluoropropylene], (FEP), and[polyvinylidene fluoride], (PVDF). Both PFA Teflon® and FEP Teflon®thermoplastics are manufactured by DuPont, Wilmington, Del. Neoflon® PFAis a polymer available from Daikin Industries. MFA Haflon® is a polymeravailable from Ausimont USA Inc. Thorofare, N.J. Preformed MFA Haflon®and FEP Teflon® tubes are available from Zeus Industrial Products Inc.Orangebury, SC. Other thermoplastics or their blends which are useful inthe practice of this invention include but not limited topoly(chlorotrifluoroethylene vinylidene fluoride), polyvinylchloride,polyolefins like polypropylene, polyethylene, polymethylpentene, ultrahigh molecular weight polyethylene, polyamides, polysulfones,polyetheretherketones, and polycarbonates.

[0044] Hollow thermoplastic tubes can be impregnated with thermallyconductive powders or fibers to increase their thermal conductance.Examples of useful thermally conductive materials include but are notlimited to glass fibers, metal nitride fibers, silicon and metal carbidefibers, or graphite. The thermal conductivity of the hollowthermoplastic tubes or impregnated thermoplastic hollow tubes useful inthis invention is greater than about 0.05 watts per meter per degreeKelvin.

[0045] Hollow tubes useful in the practice of this invention forparticle filtration and mass transfer applications such as gascontacting, liquid degassing, and pervaporation include hollow fibermembranes. Suitable membranes include hollow fibers made from[Polytetrafluoroethylene-co-perfluoropropylvinylether], (PFA), or ultrahigh molecular weight polyethylene, both available from MykrolisCorporation, Billerica, Mass.

[0046] In a preferred embodiment the twisted, plaited, or braided tubeform a continuous cord. The cord can be wound around a rectangular metalframe, as described in WO 00/44479, the distance between parallel sidesdefining the length of the exchange device. The coiled cord on the metalframe is placed in an oven below the melting point of the hollow tubes.The tubes are thermally annealed at a temperature below their meltingpoint and then cooled to set the crests or bends in the braided,plaited, or twisted tubes into the cord. Annealing of the cord tubesoccurs below the melting point at a temperature usually less than 250degrees Celsius, more preferably from 100 to 200 degrees Celsius, andfor a time ranging from 15 to 60 minutes, and more preferably for 30minutes. In an alternative embodiment the twisted, plaited, or braidedtubes can be annealed on a spool.

[0047] In another embodiment the braided or twisted tubes can bethermally annealed in a first step and then the individual tubesseparated from each other after cooling to form self supporting helicalshaped or non-circumfrential shaped single tubes. Thermal annealing setsthe crests and bends of the hollow tube so that the individual hollowtubes or cords can be separated and handled without straightening.

[0048] In one embodiment of the present invention, the thermallyannealed and set cords of hollow tubes can be joined by the methoddescribed in U.S. Pat. No. 3,315,750 included herein by reference in itsentirety. The cords can also be joined to each other and to the housingby the injection molding method described in European Patent Application0 559 149 A1 included herein by reference in its entirety. In apreferred embodiment, the method described in U.S. patent application60/117,853, filed Jan. 29, 1999 and WO 00/44479, and incorporated hereinin its entirety by reference is useful in the practice of the currentinvention.

[0049] The term unified terminal end block or unitary end structure inthe practice of this invention is meant to describe a mass or well of athermoplastic resin into which one or more hollow tubes or cords havebeen bonded or fusion bonded. FIG. 7 illustrates an example of hollowtubes fusion bonded to a thermoplastic resin to form a unified terminalend block structure and hollow tubes not fusion bonded to athermoplastic resin. U.S. patent application No. 60/117,853 describes ahollow fiber bonded to a thermoplastic resin. Optionally thermoplasticend caps having fluid connector ports or a thermoplastic housing may befusion bonded to the one or more of the unified terminal end blocks. Forpurposes of illustrating the present invention, a unified terminal endblock comprising hollow tubes, a thermoplastic resin, and athermoplastic housing is described. The housing to form a single entityconsisting solely of perfluorinated thermoplastic materials is preparedby first pretreating the surfaces of both ends of the housing before thepotting and bonding step. A unified terminal end block end structure, bywhich is meant that the braided or twisted tubes and the potting arebonded to the housing to form a single entity consisting solely ofperfluorinated thermoplastic materials is prepared by first pretreatingthe surfaces of both ends of the housing before the potting and bondingstep. This is accomplished by melt-bonding the potting material to thehousing. The internal surfaces on both ends of the housing are heatedclose to their melting point or just at the melting point andimmediately immersed into a cup containing powdered[Polytetrafluoroethylene-co-perfluoromethylvinylether] thermoplasticpotting resin available from Ausimont USA Inc. Thorofare, N.J. Since thesurface temperature of the housing is higher than the melting point ofthe potting resins, the potting resin is then fused to the thermoplastichousing. The housing is then taken out and polished with a heat gun tofuse any excess un-melted thermoplastic powder. It is preferred thateach end of the tube be treated at least twice with this pre-treatment.

[0050] The annealed twisted hollow tube cords are inserted into apoly(tetrafluoroethylene-co-perfluoro(alkyvinylether)), Teflon® PFA, orMFA shell tube. The shell tube optionally has fluid fittings fusionbonded to its surface to form an inlet and an outlet ports. The packingdensity of the tube cords within the shell tube should be in the rangeof from 3-99 percent by volume, and more preferably 20-60 percent byvolume.

[0051] Potting and bonding of the tube cords into the housing can bedone in a single step. The preferred thermoplastic resin pottingmaterial is Hyflon® MFA 940 AX resin, available from Ausimont USA Inc.Thorofare, N.J. The method comprises vertically placing a portion of abundle of the annealed and twisted hollow tube cord lengths with atleast one closed end into a temporary recess made in a pool of moltenthermoplastic polymer held in a container. The hollow tubes are held ina defined vertical position, maintaining the thermoplastic polymer in amolten state so that it flows into the temporary recess, around thehollow tubes and vertical up the fibers, completely filling theinterstitial spaces between fibers with the thermoplastic polymer. Atemporary recess is a recess that remains as a recess in the moltenpotting material for a time sufficient to position and fix the bundle ofhollow tubes in place and then will be filled by the moltenthermoplastic. The temporary nature of the recess can be controlled bythe temperature at which the potting material is held, the temperatureat which the potting material is held during hollow tube bundleplacement, and the physical properties of the potting material. The endof the hollow tube can be closed by sealing, plugging, or in a preferredembodiment, by being formed in a loop.

[0052] Once the first end of the device has been potted and fused into aunified terminal end block comprising the hollow tubes, housing andthermoplastic resin, the second end of the device is potted. The processinvolves heating the potting resins in a heating cup with an externalheating block or other heat source at a temperature in the range of fromabout 265 C to around 285 C, with a preferred range of from about 270 Cto around 280 C, until the melt turns clear and is free of trappedbubbles. A rod is inserted into the melt to create a recess or cavity.The housing and the hollow tube bundle are then inserted into thecavity. It is important to note that at this point neither the hollowtube bundle nor the housing touches the potting resin. The melted resinwill flow by gravity to fill the voids over time to pot the hollow tubesand bond to the housing simultaneously. After the potted ends arecooled, they are then cut and the lumen of the hollow tubes exposed. Thepotted surfaces are then polished further using a heat gun to melt awayany smeared or rough potted surfaces. For module with a large number ofhollow tubes, such as 2000 or more, it is possible that the module maypotting defects which can be repaired using a clean soldering iron tofuse and close the damaged areas.

[0053] Another embodiment of this invention is useful for pottinghelical cords composed of hollow tubes. Each end of the twisted orbraided hollow tubes are potted in a metal mold in a first step. Themold is slightly smaller than the inner diameter of the shell tube andcan be made from aluminum or nickel or similar alloys. After potting andcooling, the mold is removed. The ends of the hollow tubes in theunified terminal end blocks are opened by cutting as described above.After both ends of the hollow tubes have been potted, the formed unifiedterminal end block structures are inserted into a pretreated MFA or PFAshell housing tube, or end caps, and the unified terminal end blockfused to the housing tube or end caps in a short heating process.

[0054] In a preferred embodiment of this invention illustrated in FIG.3, at least one thermoplastic tube 66 is inserted into at least one ofthe fluid fittings 48 on the shell side of the exchange apparatus. It ispreferred that the tube be placed into a portion of the tube bundlenearest the fitting. The tube can be thermally bonded to the housing orpress fit into the shell fittings. The tube provides for improved flowdistribution of fluid in the device.

[0055] Fluid fitting useful for connecting the apparatus of thisinvention to sources of working and process fluid include but are notlimited to Flaretek®, Pillar®, Swagelock®, VCO®, standard pipe threadfittings, or barb fittings. In a preferred embodiment two fluidconnections are provided for the process fluid; one inlet connection forflow of fluid into the apparatus and one outlet connection for flow offluid out from the apparatus. The process fluid may flow through thetubes or across the outside of the tubes. The inlet and outletconnections for the process fluid may be bonded to the unified terminalend blocks by welding, threading, flanging, or fusion bonding to thethermoplastic. If a housing is provided for the exchange apparatus, theinlet connections for the process fluid may be bonded to the housing andor unified terminal end block by welding, threading, or flanging. In apreferred embodiment the connections are fusion bonded to the housingand or the unified terminal end block. One or more fluid connections maybe provided for flow of working fluid through the housing or for flow offiltered liquid out of the housing. The one or more connections for flowof working fluid or filtered fluid through the housing may be bonded tothe housing by welding, threading, or flanging to the housing. In apreferred embodiment the connections are fusion bonded to the housing.

General Procedure 1

[0056] Preformed hollow MFA tube tubes with 0.047 inch inside diameterand 0.006 inch thick wall thickness were obtained from Zeus IndustrialProducts Inc. Orangebury, S.C. Cords for potting were made by handtwisting pairs of these hollow MFA tubes to obtain about 12 turns perfoot of cord. A single cord was wrapped around a metal frame 8 incheswide and 18-27 inched long; it was possible to make about 75 wraps ofthe cord on the metal frame. The frame and wrapped cords were annealedin an oven for 30 minutes at 150 degrees Celsius. About 75 loops of cordeach measuring 18-27 inches in length were obtained from the rack afterannealing. Cord from a single rack or from multiple racks were gatheredand placed into a previously heat treated and MFA coated PFA tubemeasuring 16-25 inches in length. The inside diameter of the tubes was1-2.25 inch and ¼″ FlareTek® fluid fittings were bonded approximately 2inches from each end of the PFA tube. Each end of the device was pottedusing Hyflon® MFA 940 AX resin, obtained from Ausimont USA Inc.Thorofare, N.J., for about 40 hours at 275° C. Cool down of each endafter 40 hours of potting was controlled to a rate of 0.2° C./min to150° C. The unified terminal block ends were cleared of resin and thehollow tubes opened by machining the end portion of the potted deviceusing a lathe or knife. Fluid fittings for the potted exchanger weremade by scoring a pipe thread onto each end of the tube or by thermallyfusing an end cap onto the tube.

EXAMPLE 1

[0057] A prototype heat exchanger having a housing with a 1 inch insidediameter PFA tube was prepared by Procedure 1 except that the tubes werenot twisted or annealed. The device contained 150 tubes of straight MFAtube measuring 15 inches in length.

[0058] The prototypes was tested under the following conditions. Hotwater at a temperature of 63° C. was fed into the tube side of thedevice at a flow rate of approximately 1750 ml/min. Cold water at atemperature of 19° C. was fed into the shell side of the device at aflow rate of approximately 1070 ml/min. The hot and cold water pathsflowed countercurrent to one another. The inlet and outlet temperaturesand the flow rates were recorded every five minutes for the tube andshell side fluid streams for one hour. The results from this experimentare detailed in Table 1 shown in FIG. 6. Under these conditions the coldwater was heated from 18.9° C. to 38.8° C. and a total of 1486 watts ofenergy was exchanged between the two fluids.

EXAMPLE 2

[0059] A prototype heat exchange apparatus having a housing with a 1inch inside diameter PFA tube was prepared by Procedure 1 except that itcontained about 150 hollow MFA tubes twisted together with about 12twists per foot. The twisted cords were annealed on a metal rack toyield approximately 75 cords measuring about 15 inches in length.

[0060] The prototype was tested under the following conditions. Hotwater at a temperature of 55° C. was fed into the tube side of thedevice at a flow rate of approximately 1650 ml/min. Cold water at atemperature of 19° C. was fed into the shell side of the device at aflow rate of approximately 1070 ml/min. The hot and cold water pathsflowed countercurrent to one another. The inlet and outlet temperaturesand the flow rates were recorded every five minutes for the tube andshell side fluid streams for one hour. The results from this experimentare detailed in Table 1 in FIG. 6. Under these conditions the cold waterwas heated to from 18.9° C. to 44.0° C. and a total of 1874 watts ofenergy was exchanged between the two fluids.

EXAMPLE 3

[0061] This prospective example shows how a wafer processing toolincluding the exchange apparatus of this invention can be used to heatliquids used for cleaning semiconductor wafers.

[0062] An exchange apparatus having about 650 twisted hollow MFA tubes,325 pairs, can be thermally annealed and fusion bonded in a 2 inchinside diameter PFA tube using the methods of Procedure 1. The length ofthe device can be about 18 inches and has a liquid volume of about 300millliliters. The device is part of a wafer processing tool and isconnected at its inlet fluid connection to an in-line to a source ofaqueous 10% hydrochloric acid containing about 1 percent by volumehydrogen peroxide. The outlet of the exchange device is connected to avalve, optional stop suck back valve, and nozzle for dispensing theaqueous acid solution onto a substrate to be cleaned. One of the fluidinlet connections on the shell side of the exchange device is connectedin-line to a source of hot water. Hot deionized water is commonlyavailable in a semiconductor factory at a temperature of about 75degrees Celsius. The heated water passing through the shell side of theexchange device heats the acid solution contained within the tubes ofthe exchange apparatus. After a variable time of no fluid flow, thevalve at the outlet of the exchange device is opened and heated aqueousacid and oxidant is dispensed onto the wafer where it is used to cleanthe wafer. The valve is closed and liquid acid and oxidant flows intothe hollow tubes of the exchange apparatus where it is heated for thenext dispense.

EXAMPLE 4

[0063] This prospective example shows how an exchanger for cross flowfiltration may be made utilizing thermally annealed, plaited, poroushollow PFA tubes.

[0064] A prototype filtration device having a housing with a 1 inchdiameter PFA tube was prepared by Procedure 1 except that 150 hollowporous PFA fibers having a 550 micron outside diameter, available fromMykrolis Corporation, Billericia, Mass., are substituted for the nonporous hollow MFA tubes. The hollow fibers can be plaited 3 per strandand can be wound on a rack measuring 15 inches in length. The plaitedand wound hollow fibers can be thermally annealed at about 150 Celsiusto set the plait and length of the hollow fibers. The thermally annealedand plaited hollow fibers are assembled into an apparatus according tothe method disclosed in WO 0044479.

[0065] The housing for this device contains inlet and outlet portconnections for flow of a fluid containing insoluble suspended materialslike colloids, gels, or hard particles. Examples of fluids containingsuspended solid particles include alumina in a chemical mechanicalpolishing slurries, examples of colloids in fluids can include silica.The fluid containing the insoluble suspended material flows through theinsides of the porous hollow fiber tubes. The housing has a single fluidflow port connection for flow of filtered liquid away from the housing.A portion of the liquid containing the suspended solids flows across theplaited porous hollow tubes; some of the solids are retained by theporous membrane and a portion of filtered liquid flows through themembrane and out of the fluid port on the housing.

EXAMPLE 5

[0066] This prospective example shows how an exchange apparatus for masstransfer of a gas into a liquid may be made utilizing thermallyannealed, plaited, porous hollow PFA tubes.

[0067] A prototype filtration device having a housing with a 1 inchdiameter PFA tube can be prepared by Procedure 1 except that 150 hollowporous PFA fibers having a 550 micron outside diameter, available fromMykrolis Corporation, Billericia, Mass., are substituted for the 150hollow MFA tubes. The hollow fibers can be plaited 3 per strand and canbe wound on a rack measuring 15 inches in length. The plaited and woundhollow fibers can be thermally annealed at about 150 C to set the plaitand length of the tubes. The thermally annealed and plaited hollowfibers can be assembled into an apparatus according to the methoddisclosed in WO 0044479.

[0068] The housing for this device can have inlet and outlet portconnections for flow of deionized water through the insides of theporous hollow fiber tubes. One of the housing's two ports can be usedfor connection to a source of ozone gas generated by an ozone generator,for example Astex 8400 ozone generator available from Astex, Woburn,Mass. The ozone gas dissolves in the water by permeating through theporous plaited hollow PFA tubes. Excess ozone gas is vented through thehousing's second port. Water exiting the insides of the tubes containsozone gas dissolved in the water. This ozonated water is useful forcleaning wafers using a modified RCA cleaning processes.

EXAMPLE 6

[0069] This example illustrates a heat exchange apparatus of thisinvention with twenty thin walled hollow PFA tubes. The device was usedto heat flowing water in-line.

[0070] A 0.5 inch OD PFA tube of length 17 inches was used as a housingconduit. The housing conduit had inlet and outlet ports. The housingconduit was fusion bonded using PFA potting material at each end totwenty six 1.05 mm ID PFA tubes with wall thickness 0.15 mm. Two J-typethermocouples were positioned in separate flow through housings. Onethermocouple was connected to the inlet port of the exchange apparatushousing conduit and the second thermocouple was connected to the outletport of the heater device housing conduit. In operation process waterflows through the inlet thermocouple housing, into the exchangerapparatus housing, and through the hollow tubes. Working or exchangefluid passed through an inlet thermocouple housing and into the shellside of the housing in a counter current fashion where it contacted theoutsides of the hollow tubes. The exchange or working fluid then passesthrough the outlet port on the shell side of the housing conduit andthrough a second outlet thermocouple housing. Process water flowingthrough the exchange apparatus tubes exits the tubes through a secondoutlet thermocouple housing. With a flow rate of 1000 milliliters perminute of water at a temperature of about 16 degrees Celsius flowinginto the shell side of the device, water flowing into the tubes at atemperature of 55.5 degrees Celsius and a flow rate of 260 millilitersper minute was cooled to 33.1° C. on exiting the tubes. The performanceof this apparatus at different tube side flow rates is summarized inFIG. 8.

EXAMPLE 7

[0071] This example illustrates a heat exchange apparatus of thisinvention with 680 thin walled hollow MFA tubes. The device was used tocool flowing water in-line.

[0072] A prototype heat exchange apparatus having a PFA housing with a2.25 inch inside diameter 32 inch length was prepared by Procedure 1except that it contained about 680 hollow MFA tubes twisted togetherwith about 12 twists per foot. The twisted cords were annealed on ametal rack to yield cords measuring about 34 inches in length. Inletfluid fittings on the housing shell side were ½″ Flaretek®; they were 27inches apart and 2.5 inches from the ends of the device. The housingfluid fittings for tube side flow were ¾″ Flaretek® and were fusionbonded to the housing tube.

[0073] The prototype was tested under the following conditions. Hotwater at a temperature of 70.1° C. was fed into the tube side of thedevice at a flow rate of approximately 4.4 liters per minute. Cold waterat a temperature of 14.5° C. was fed into the shell side of the deviceat a flow rate of approximately 6.6 liters per minute. The hot and coldwater paths flowed countercurrent to one another. The inlet and outlettemperatures and the flow rates were recorded using an Agilent datalogger. The results from this experiment are detailed in the Table inFIG. 9. Under these conditions the hot water in the tubes was cooledfrom 70.1° C. to 22.9° C. and a total of 14,400 watts of energy wasexchanged between the two fluids. The performance of this apparatus atother flow rates is summarized in FIG. 9.

What is claimed:
 1. An exchange apparatus comprising: a) a plurality ofthermoplastic hollow tubes, each hollow tube having two end portions andhollows passing therebetween; b) at least one of said end portions ofsaid hollow tubes being fusion bonded at least at its periphery througha thermoplastic resin to form a unified terminal end block in which theend portions of said hollow tubes are fluid tightly bonded together in afused fashion with the thermoplastic resin; c) said unified terminal endblock having through hole communication with the hollows of the unbondedportions of said tubes; and d) said unified terminal end block having afirst fluid inlet connection to supply a first fluid to said hollowtubes and a first fluid outlet connection to remove said first fluidfrom said hollow tubes.
 2. The exchange apparatus of claim 1, furthercomprising: a) a housing fusion bonded to at least one of said unifiedterminal end blocks containing said hollow tubes; and b) said housinghaving at least one connection port for transport of at least one fluidthrough the exchange device.
 3. The apparatus of claim 1, wherein thethermoplastic hollow tubes are non-circumfrential.
 4. The apparatus ofclaim 1, wherein the thermoplastic hollow tubes are plaited into a cord.5. The apparatus of claim 1, wherein the thermoplastic hollow tubes areplaited into a cord which is thermally annealed to set the plait.
 6. Theapparatus of claim 1, wherein said hollow tubes are comprised of athermoplastic or a blend thereof chosen from the group consisting of[Polytetrafluoroethylene-co-perfluoromethylvinylether],[Polytetrafluoroethylene-co-perfluoropropylvinylether],[Polytetrafluoroethylene-co-hexafluoropropylene], polypropylene,polymethylpentene, and ultra high molecular weight polyethylene.
 7. Theapparatus of claim 1, wherein the thermoplastic hollow tubes are porous.8. The apparatus of claim 1 wherein said thermoplastic tubes areimpregnated with a thermally conductive material.
 9. The apparatus ofclaim 1 wherein the cord comprises at least 1 plait.
 10. The apparatusof claim 2, wherein at least one housing fluid connection has an insertfor fluid flow distribution.
 11. The apparatus of claim 2, wherein thethermoplastic hollow tubes are non-circumfrential.
 12. The apparatus ofclaim 2, wherein the thermoplastic hollow tubes are plaited into a cord.13. The apparatus of claim 2, wherein the thermoplastic hollow tubes areplaited into a cord which is thermally annealed to set the plait. 14.The apparatus of claim 2, wherein said hollow tubes are comprised of athermoplastic or a blend thereof chosen from the group consisting of[Polytetrafluoroethylene-co-perfluoromethylvinylether],[Polytetrafluoroethylene-co-perfluoropropylvinylether],[Polytetrafluoroethylene-co-hexafluoropropylene], polypropylene,polymethylpentene, and ultra high molecular weight polyethylene.
 15. Theapparatus of claim 2, wherein the tubes are porous.
 16. The apparatus ofclaim 2 wherein said thermoplastic tubes are impregnated with athermally conductive material.
 17. The apparatus of claim 2 wherein thecord comprises at least 1 plait.
 18. An exchange apparatus comprising:a) A plurality of thermoplastic hollow tubes, each hollow tube havingtwo end portions and hollows passing therebetween and at least one tubebeing non-circumfrential b) At least on of said end portions of saidhollow tubes being bonded at least at its periphery through athermoplastic resin in which the end portions of said hollow tubes arefluid tightly bonded wit the thermoplastic resin; c) Said unifiedterminal end block having through hole communication with the hollows ofthe unbonded portions of said tubes; and d) Said unified terminal endblock having a first fluid inlet connection to supply a first fluid tosaid hollow tubes and a first fluid outlet connection to remove saidfirst fluid from said hollow tubes.
 19. The apparatus of claim 18,wherein the thermoplastic hollow tubes are porous.
 20. A method ofmaking an exchange apparatus comprising: a) forming a bundle comprisedof a plurality of thermoplastic hollow tubes having a first end and asecond end; b) fusing the first end of one or more said bundles ofthermoplastic hollow tubes with a thermoplastic resin to form a firstunified terminal end block; c) fusing the second end of one or more saidbundles of thermoplastic hollow tubes with a thermoplastic resin to forma second unified terminal end block; d) opening the tube ends of thefirst and second unified terminal end blocks to provide for fluid flowthrough the hollow tubes fused with the thermoplastic resin.
 21. Themethod of claim 20, wherein said tubes are comprised of a thermoplasticor a blend thereof chosen from the group consisting of[Polytetrafluoroethylene-co-perfluoromethylvinylether],[Polytetrafluoroethylene-co-perfluoropropylvinylether],[Polytetrafluoroethylene-co-hexafluoropropylene], polypropylene,polymethylpentene, and ultra high molecular weight polyethylene.
 22. Themethod of claim 20 wherein the opened ends of said hollow tubes fused tosaid thermoplastic resin have substantially the same cross section asthe unbonded portion of the hollow tubes.
 23. The method of claim 20further comprising making a bundle from a plurality of thermoplastichollow tubes plaited to form at least one cord.
 24. The method of claim23, further comprising annealing the cord below the melting point of thethermoplastic hollow tubes to set the plait in the tubes in the cord.25. The method of claim 24, wherein said annealed cords are separatedinto individual thermoplastic hollow tubes and are then bonded with thethermoplastic resin as a bundle of non-circumfrential hollow tubes. 26.The method of claim 20 further comprising bonding at least one fluidconnection port to said unified terminal end blocks.
 27. The method ofclaim 26 further comprising bonding a thermoplastic housing to saidfirst and second unified terminal end blocks.
 28. A method of using theexchange apparatus of claim 1 for heat transfer from a first fluid to asecond fluid the method comprising: a) flowing a first fluid on a firstside of said hollow tubes; b) flowing a second fluid on a second side ofsaid hollow tubes; c) transferring energy between said first and secondfluids through the wall of the thermoplastic hollow tubes.
 29. Themethod of claim 28 wherein said fluid is a photoresist, anantireflective coating, a resist stripper, or a photoresist developer.30. The method of claim 28 wherein said fluid is a spin on dielectric.31. The method of claim 28 wherein said fluid is a fluid comprisingcopper ions.
 32. The method of claim 28 wherein said fluid is chosenfrom the group consisting of an acid, a base, an oxidizer, and mixturesthereof.
 33. The method of claim 28 wherein said liquid is an organicliquid.
 34. The method claim 28 wherein said second fluid is chosen fromthe group consisting of an inert gas, water, polyethylene glycolcompositions, and steam.
 35. The method of claim 28 wherein the firstfluid a gas.
 36. The method of using the exchange apparatus as in eitherclaim 7 or claim 18 for cross flow filtration of a fluid, the methodcomprising: a) flowing a first fluid containing insoluble suspendedmaterial on a first side of said hollow porous tubes; and b) filtering aportion of said first fluid through said hollow porous tubes, saidhollow porous tubes retaining a portion of the insoluble suspendedmaterial and passing a portion of said fluid through the hollow poroustubes.
 37. The method of using the exchange apparatus as in either claim7 or claim 18 for mass transfer between fluids, the method comprising:a) flowing a first fluid on a first side of said hollow porous tubes; b)flowing a second fluid on a second side of said hollow porous tubes; andc) dissolving a portion of said second fluid into said first fluid. 38.The method of claim 37 wherein the first fluid is an aqueous solutionand the second fluid is a gas.
 39. An exchange apparatus adapted to beconnected in-line with a fluid flow circuit comprising: a) A housingprovided with fluid fittings; b) an exchange core located within saidhousing, said exchanger core containing a plurality ofnon-circumferential tubes fabricated from a thermoplastic resin; c) saidtubes arranged in a lengthwise direction and having two end portionsbeing fusion bonded at their periphery through a thermoplastic resin toform unified terminal end blocks in which the end portions of saidnon-circumferential tubes are fluid tightly bonded in a fused fashionyet allow fluid communication therethrough; and d) said housing having afirst fluid inlet to supply a first fluid to said first end of theexchange core to be contacted with a second fluid and a first fluidoutlet connection to remove said contacted first fluid from saidnon-circumferential tubes and said housing having a first fluid inletconnection to supply a second fluid to be contacted with said firstfluid to said volume formed between the inner wall of the housing andthe non-circumferential tubes and a second outlet connection to removesaid contacted second fluid.
 40. An apparatus for processing waferscomprising the exchange apparatus of any one of claims 1, 18, or
 37. 41.A method for producing a thermoplastic hollow tube with increasedboundary layer disruption, the method comprising: a) Securing athermoplastic tube for an exchange apparatus; and b) Distorting thestructure of the hollow tube such that it becomes non-circumfrential.